Method and apparatus for facilitating physiological coherence and autonomic balance

ABSTRACT

Method and apparatus for determining the state of entrainment between biological systems which exhibit oscillatory behavior such as heart rhythms, respiration, blood pressure waves and low frequency brain waves based on a determination of heart rate variability (HRV) and an evaluation of the power spectrum thereof. Entrainment reflects a harmonious balance between the two branches of the autonomic nervous system within the body. This internal state of heightened physiological efficiency enhances health and promotes optimal performance. According to one embodiment a method is used to determine the entrainment level based on an entrainment parameter related to HRV, The method first determines the power distribution spectrum (PSD) and then calculates an entrainment parameter (EP), which is a measure of the power distribution in the HRV spectrum. High EP values occur when this power is concentrated within a relatively narrow range of frequencies, and lower values when the power is distributed over a broader range of frequencies. In one embodiment, an apparatus is provided for monitoring the heart beat and presenting this information via a personal computer, handheld device, or other processing means.

TECHNICAL FIELD

The present invention relates generally to the evaluation of heart ratevariability, and specifically to the analysis of the power spectrumdistribution thereof.

BACKGROUND ART

With the growing complexity of life, the relation between physiologicalconditions and emotional health becomes of increasing interest. Manystudies have shown that stress and other emotional factors increase therisk of disease, reduce performance and productivity and severelyrestrict the quality of life. To this end, the medical communitiesaround the world continually seek remedies and preventive plans.Recently a focus on the self-regulation of systems within the body hasled to research in the areas of biofeedback, etc.

In the last 25 years, a variety of new techniques have been introducedas alternatives to more traditional psychotherapies or pharmaceuticalinterventions for improving mental and/or emotional imbalances. Inaddition to the more psychological approaches like cognitivere-structuring and neurolinguistic programming, psychologists haveemployed several techniques from Eastern cultures to “still the mind”during focused meditation. In yoga, for example, one generally focuseson the breath or parts of the brain, whereas in qigong one focuses onthe “dan tien” point (below the navel). In a Freeze Frame® (FF)technique, developed by the Institute of Heart Math in Boulder Creek,Calif., one focuses attention on the area around the heart. All thesetechniques focus attention upon areas of the body which are known tocontain separate but interacting groups of neuronal processing centers,and biological oscillators with which they interact. The heart, brain,and the intestines contain biological oscillators known as pacemakercells. By intentionally focusing attention on any one of theseoscillator systems, one can alter its rhythms. This is at least true forthe brain (meditation), yogic breathing (respiration), the heart (FF),and most likely the gut (qigong), since it is also regulated by theautonomic nervous system (ANS). The body also contains other oscillatingsystems such as the smooth muscles of the vascular system. We havepreviously shown that this system, measured by recording pulse transittime (PTT), as well as the brain, measured by an electroencephalograph(EEG), the heart, measured by a heart rate variability (HRV), and therespiration system, measured by the respiration rate, can all entrain.Furthermore, they all synchronize to a frequency varying around 0.1Hertz (Hz). Thus, one can intentionally bring these systems, acting ascoupled biological oscillators, into synchrony with each other.

The FF technique is a self-management technique by which one focuses onthe heart to disengage from moment-to-moment mental and emotionalreactions. A study utilizing the FF technique in a psychologicalintervention program with HIV-positive subjects resulted in significantreductions in life-stress, state and trait anxiety levels, andself-assessed physical symptoms. Two other studies with healthyindividuals using the FF technique to enhance positive emotional statesshowed increased salivary IgA and increased sympathovagal balance.Increased sympathovagal balance is known to protect against detrimentalphysiological effects associated with overactive sympathetic outflowfrom the brain. Other studies have shown the techniques to be effectivein improving autonomic balance and decreasing the stress hormonecortisol and increasing DHEA, improving glycemic regulation indiabetics, reducing blood pressure in hypertensive individuals andsignificantly reducing psychological stressors such as anxiety,depression, fatigue and overwhelm in many diverse populations.

Sympathovagal balance has been measured using various techniques. Forexample, individuals can be trained to consciously control their heartrate using biofeedback techniques. However, the enhanced parasympatheticactivity is probably mediated through control of respiration. Neutralhypnosis and operant conditioning of heart rate have been demonstratedto decrease in the sympathetic/parasympathetic ratio by increasingparasympathetic activity independent of controlled breathing techniques.The FF technique does not require biofeedback equipment nor does itrequire conscious control of respiration although a short breathingprotocol is used this technique. Our results suggest that emotionalexperiences play a role in determining sympathovagal balance independentof heart rate and respiration. The shifts in sympathovagal balancetoward increased low-frequency (LF) and high frequency (HF) power(measures of heart rate variability) were physiological manifestationsof experiencing the emotional state of appreciation. The FF techniquefocuses on genuinely experiencing the feelings of sincere appreciationor love, in contrast to visualizing or recalling a previous positiveemotional experience.

The results of our studies indicate that relatively short periods ofpractice of the FF technique and other tools developed by the Instituteof HeartMath leads to either an “entrainment” or “internal coherence”mode of heart function (described in greater detail below). Mostsubjects who are able to maintain these states report that the intrusionof random thoughts is greatly reduced and that it is accompanied byfeelings of deep inner peace and heightened intuitive awareness.

We also observed that positive emotional states, which lead to theentrainment mode, generated marked changes in the dynamic beatingpatterns of the heart. A method for quantifying and analyzing andquantifying these heart rhythms is called analysis of heart ratevariability (HRV). The normal resting heart rate in healthy individualsvaries dynamically from moment to moment. Heart rate variability, whichis derived from the electrocardiogram (ECG) or pulse, is a measure ofthese naturally occurring beat-to-beat changes in heart rate and is animportant indicator of health and fitness. HRV is influenced by avariety of factors, including physical movement, sleep and mental andactivity, and is particularly responsive to stress and changes inemotional state. The analysis of HRV can provide important informationrelative to the function and balance of the autonomic nervous system, asit can distinguish sympathetic from parasympathetic regulation of heartrate. Decreased HRV is also a powerful predictor of future heartdisease, increased risk of sudden death, as well as all-cause mortality.

Frequency domain analysis decomposes the heart rate tachogram orwaveform into its individual frequency components and quantifies them interms of their relative intensity, in terms of power spectral density(PSD). By applying spectral analysis techniques to the HRV waveform, itsdifferent frequency components, which represent the activity of thesympathetic or parasympathetic branches of the autonomic nervous system,can be discerned. The HRV power spectrum is divided into three frequencyranges or bands: very low frequency (VLF), 0.033 to 0.04 Hz; lowfrequency (LF), 0.04 to 0.15 Hz; and high frequency (HF), 0.15 to 0.4Hz.

The high frequency (HF) band is widely accepted as a measure ofparasympathetic or vagal activity. The peak in this band corresponds tothe heart rate variations related to the respiratory cycle, commonlyreferred to as respiratory sinus arrhythmia. Reduced parasympatheticactivity has been found in individuals under mental or emotional stress,suffering from panic, anxiety or worry and depression.

The low frequency (LF) region can reflect both sympathetic andparasympathetic activity, especially in short-term recordings.Parasympathetic influences are particularly present when respirationrates are below 7 breaths per minute or when an individual takes a deepbreath. This region is also called the “baroreceptor range” as it alsoreflects baroreceptor activity and at times blood pressure wave activityand resonance.

When an individual's HRV pattern and respiration are synchronized orentrained, as can happen spontaneously in states of deep relaxation,sleep or when using techniques to facilitate autonomic balance such asFreeze-Frame and the Heart Lock-In, the frequency at which theentrainment occurs is often near 0.1 Hertz. This falls in the center ofthe LF band and could be misinterpreted as a large increase insympathetic activity, when in reality it is primarily due to an increasein parasympathetic activity and vascular resonance. Sophisticatedmodeling techniques have shown that in normal states, about 50% of thetotal power in the LF band is explained by neural signals impinging onthe sinus node which are generated at a central level, and the majorityof the remaining power is due to resonance in the arterial pressureregulation feedback loop. The sympathetic system does not appear toproduce rhythms that appear much above frequencies of 0.1 Hz, while theparasympathetic can be observed to operate down to frequencies of 0.05Hz. Thus, in individuals who have periods of slow respiration rate,parasympathetic activity is modulating the heart rhythms at a frequencythat is in the LF band. Therefore, in order to discriminate which of theANS branches is pumping power into the LF region, both respiration andPTT should be simultaneously recorded and considered.

The increase in LF power while in the entrainment mode may representincreased baroreceptor afferent activity. It has been shown that the LFband reflects increased afferent activity of baroreceptors. The LF bandhas indeed been shown to reflect baroreceptor reflex sensitivity and isaffected by physiological states. Increased baroreceptor activity isknown to inhibit sympathetic outflow from the brain to peripheralvascular beds, whereas stress increases sympathetic outflow and inhibitsbaroreflex activity. The increase in LF power seen during the state ofdeep sustained appreciation may have important implications for thecontrol of hypertension, since baroreflex sensitivity is reduced inthese individuals.

There is a noticeable and obvious transition after the FF interventionto the entrainment mode which can be seen in the HRV waveforms and PSDdata. In addition, many subjects report that they are able to use the FFtechnique while they were in a “tense” conversation with someone andstarting to react. Even in these conditions, the HRV waveforms indicatethat they were able to shift to and maintain the entrainment state.

From tachogram data, it can be seen that, as one moves from a state offrustration to one of sincere appreciation a transition occurs in thewaveforms from a noisy wave of large amplitude to a non-harmonic waveform of similar amplitude (entrainment). We have also identified anadditional state we call “amplified peace” to indicate this specialemotional state of very deep peace and inner harmony. In this state, theHRV waveform becomes a smaller amplitude wave (internal coherence). Ingeneral, the transition in the frequency domain (PSD) is from awide-band spectrum of moderate amplitude to a narrow-band spectrumaround 0.1 Hz of very large amplitude (entrainment) and then to awide-band spectrum of very small amplitude (internal coherence).

In most individuals, small to near-zero HRV, as just described, is anindicator of a potentially pathological condition or aging because itconnotes loss of flexibility of the heart to change in rate or adecreased flow of information in the ANS. However, in trained subjects,it is an indication of exceptional self-management of their emotions andautonomic nervous system because their HRV is normally large and theshift into the internal coherence mode is a result of intentionallyentering the amplified peace state. This is very different from apathological condition underlying lowered HRV (in such cases the HRV isalways low). The connection between emotional states and HRV couldpossibly account for the occasional observation of low HRV in otherwisehealthy individuals which has detracted from the clinical utility of HRVanalysis for unequivocally predicting disease.

During the condition of internal coherence, the electromagnetic energyfield produced by the heart, as seen in a fast Fourier transform (FFT)analysis of an electrocardiogram (ECG) signal, is a clear example of acoherent electromagnetic field. Recent advances in the understanding ofthe interaction between coherent signals and noise in nonlinear systemshas resulted in the prediction that these nonthermal, coherentelectromagnetic signals may be detected by cells. Further evidencesuggests that coherent electromagnetic fields may have importantimplications for cellular function. For example, it has been recentlydemonstrated that nonthermal, extremely low frequency electromagneticsignals may affect intracellular calcium signaling. In addition,coherent electromagnetic fields have been shown to produce substantiallygreater cellular effects on enzymatic pathways, such as ornithinedecarboxylase activity, than incoherent signals. This fact suggests thatthe state of internal coherence may also affect cellular function andprovides a potential link between emotional states, autonomic function,HRV and cellular processes.

Conscious focus of attention and/or positive emotions has been shown tosignificantly influence HRV and PSD. The results of our research supportprevious work and suggest that psychological interventions whichminimize negative and enhance positive emotional states maysignificantly impact cardiovascular function.

The results of work in this area demonstrate that sincere feelings ofappreciation produce a power spectral shift toward LF and HF activityand imply that 1) the major centers of the body containing biologicaloscillators can act as coupled electrical oscillators, 2) theseoscillators can be brought into synchronized modes of operation viamental and emotional self-control, and 3) the effects on the body ofsuch synchronization are correlated with significant shifts inperception and cardiovascular function. It is suggested that positiveemotions lead to alterations in sympathovagal balance which may bebeneficial in the treatment of hypertension and reduce the likelihood ofsudden death in patients with congestive heart failure and coronaryartery disease.

There is a need to provide quantified information regarding the balanceof the ANS which is easily used and does not require extensivebiofeedback equipment. There is further a need for a mobile method ofmonitoring this balance for use in everyday life.

DISCLOSURE OF INVENTION

The present invention provides a method of measuring certain bodyrhythms, and then analyzing this information to indirectly determine theentrainment state which is also reflective of balance between thesympathetic and parasympathetic portions of the autonomic nervoussystem.

According to one embodiment of the present invention, a method includesthe steps of sampling a heart beat of a subject, determining a heartrate variability (HRV) of the heart beat as a function of time (HRV(t)),expressing HRV(t) as a function of frequency (HRV(f)), determining adistribution of frequencies in HRV(f), selecting a peak frequency ofHRV(f), determining the energy in said peak frequency (E_(peak)),determining the energy in frequencies below said peak frequency(E_(below)) and above said peak frequency (E_(above)), determining aratio of E_(peak) to E_(below) and E_(above), and providing to thesubject, in a first presentation format, a representation of a firstparameter related to said ratio.

According to one aspect of the present invention, an apparatus includessampling means adapted to sample a heart beat of a subject for a firstpredetermined time period, a display unit, a processing unit coupled tothe sampling means and the display unit, wherein the processing unit isadapted to determine a heart rate variability (HRV) of the heart rate bymeasuring the interval between each beat during the first predeterminedtime period, wherein the HRV is a function of time, determine afrequency distribution of the HRV, the frequency distribution having atleast one peak, the at least one peak including a first number offrequencies, calculate a first parameter of the frequency distributionof the HRV, wherein the first parameter is a ratio of the area under theat least one peak to the area under the rest of the frequencydistribution, and outputting the first parameter to the display unit forpresentation to the subject.

According to one aspect of the present invention, a method includes thesteps of receiving heart rate variability (HRV) information, the HRVinformation comprising the time intervals between each heart beat of asubject during a first predetermined time period, expressing the HRV asa function of frequency, determining the power in said HRV over a firstrange of frequencies, selecting a power peak in said first range offrequencies, calculating a first parameter relating the power in saidselected power peak to the power in said HRV over a second range offrequencies, presenting the first parameter to the subject.

BRIEF DESCRIPTION OF DRAWINGS

The present invention may be more fully understood by a description ofcertain preferred embodiments in conjunction with the attached drawingsin which:

FIG. 1 illustrates in highly diagrammatic form the way in which thesympathetic and parasympathetic subsystems of the autonomic nervoussystem (ANS) of a higher organism are believed to mutually affect heartrate variability (HRV);

FIG. 2 illustrates a power spectrum distribution (PSD) of the HRVdetermined in accordance with one embodiment of the present invention;

FIG. 3 illustrates, for each of four distinct ANS states, thecharacteristic time domain HRV and the corresponding PSD;

FIGS. 4A to 4C illustrate a subject's time domain HRV, pulse transittime, and respiration rates, and the corresponding PSDs, before andafter the subject consciously performs an emotional self-regulationprotocol specifically designed to improve the balance of the ANS;

FIG. 5 illustrates an apparatus for measuring HRV and calculating thedegree of entrainment, which as previously described is also anindicator of increased autonomic balance (AB) according to oneembodiment of the present invention;

FIG. 6 illustrates one format for simultaneously displaying HRV, and theentrainment ratio, as determined in accordance with the presentinvention;

FIGS. 7A-7E illustrate in flow chart form a process for calculating ABin accordance with the present invention;

FIGS. 8A-8F illustrate the steps of the process of FIGS. 7A-7E;

FIG. 9 illustrates a hand-held apparatus for calculating AB; and

FIGS. 10-12 illustrate three different sequences of graphic displayswhich provide animated visual representations of the achieved level ofentrainment, as determined according to one embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following description of the invention and its various aspectsand embodiments, we will be using certain terms. For convenience ofreference, our preferred definitions thereof are as follows:

As noted above, Freeze-Frame® is one of the tools used in the HeartMathsystem of self-management. It consists of consciously disengaging themental and emotional reactions to either external or internal events andthen shifting the center of attention from the mind and emotions to thephysical area around the heart while focusing on a positive emotion suchas love or appreciation. This tool thus allows the individual to shiftfocus of attention from the mind to the heart. Such a shift results in awider and more objective perception in the moment.

As used hereafter, the term “appreciation” shall mean the state in whichthe subject has clear perception or recognition of the feelings ofsincere or active appreciation for someone or something. It is theheart-felt feeling of appreciation that is associated with the HRVchanges, as contrasted with the mental concept of appreciation whichdoes not appear to produce such HRV changes. The term “amplified peace”shall mean an inner state in which a much deeper state of peace andcenteredness is felt than is normally experienced. One also has a senseof standing on the threshold of a new dimension of awareness in thisstate. There is a sense of inner equilibrium and an awareness that onehas accessed a new domain of intuition. As with any experiential state,it is difficult to find words that adequately describe it. This is not astate that one normally walks around in but rather enters for relativityshort time periods. However, with practice at staying focused in theheart, the ratios of time in this state can be increased. It can also bedescribed as similar to those moments that one sometimes has when at thebeach or in the forest when one feels an especially deep contact withnature or with oneself that is beyond one's normal experience. It isoften in these moments that we find the answers to the deeper issues orproblems that we experience.

By the term “biological oscillators” we mean cells or groups of cellsthat produce rhythmic oscillation. When the instantaneous systemicarterial pressure is continuously recorded, fluctuations with each heartbeat and with each breath are seen. This rhythmic activity in theautonomic nervous system appears to be supported by at least threebiological oscillator systems: 1) centrogenic rhythms in brainstemnetworks with facultative coupling (entrainment) with the respiratoryoscillator, 2) the baroreceptor feedback network, and 3) theautorhythmicity of the vascular smooth muscle. The fact that each of theoscillators can develop different frequencies and that the phase-lagsbetween the oscillations may vary easily explains the general experiencethat blood pressure waves are quite variable and unpredictable. Theexistence of several oscillators with similar basic frequencies enablessynchronization and entrainment between oscillators. Thus, we can assumethat states of regular and steady blood pressure waves are theexpression of the entrained action of the complex multi-oscillatorysystem.

Arterial pulse transit time (PTT) is a measure of the speed of travel ofthe arterial pulse wave from the heart to some peripheral recordingsite. It is used as a non-invasive method to monitor the elasticity ofthe artery walls and to indicate changes in blood pressure on abeat-to-beat basis. The arterial pressure pulse is a wave of pressurewhich passes rapidly along the arterial system. The pulse wave velocity(4 to 5 m/sec) is much faster than the velocity of blood flow (<0.5m/sec). The pulse wave velocity varies directly with pressure-relatedchanges in the elasticity of the arterial wall. The more rigid orcontracted the arterial wall, the faster the wave velocity. From this,it follows that PTT should vary inversely with blood pressure. Commonestimates of the magnitude of this effect indicate that PTT varies byabout 1 ms per mm Hg change in pressure.

We will also be describing the results of certain studies conducted inour laboratories. In order to more fully appreciate the nature andconditions of such studies, we wish to describe our key procedures:

For in-the-lab studies, preselected individuals trained in the FFtechnique are seated in straight, high backed chairs to minimizepostural changes, fitted with ECG electrodes, and then given a 10-minuterest period. ECG measurements are recorded during the rest period andthe last 5 minutes are used as a baseline period. Recordings arecontinued while the subjects are asked to utilize the FF technique andconsciously focus on a loving state for the next 5 minutes. A selectednumber of subjects are assessed at each session. After informed consentis obtained, and prior to each session, subjects are asked to refrainfrom talking, falling asleep, exaggerated body movements orintentionally altering their respiration. Subjects are carefullymonitored to ensure there are no exaggerated respiratory or posturalchanges during the session.

The same subjects are asked to wear ambulatory ECG recorders for a24-hour period which includes a normal business day in their work place.They are asked to use the FF technique on at least three separateoccasions, when they are feeling stress or out of balance. They areinstructed to press the recorder's marker button each time they use theFF technique. This portion of a study is designed to assess ANS balancein a real-life stressful environment and to determine the efficacy ofthe FF technique to consciously improve sympathovagal balance. Ingeneral, Ag/AgCl disposable electrodes are used for all bipolar ECGmeasurements. The positive electrode is located on the left side at the6th rib, and the reference are placed in the right supraclavicularfossa. Grass model 7P4 amplifiers are used for ECG amplification.Respiration is monitored with a Resp-EZ piezoelectric belt around thechest. A Grass model 80 cardiac microphone is used when the bloodpressure wave is recorded for calculation of pulse transit time (PTT).The PTT interval is the time between the peak of the R-wave of the ECGand the appearance of the pulse wave associated with that same cardiaccontraction at the index finger on the left hand. In the out-of-labstudies, ambulatory ECG recording is accomplished with a Del Mar Holterrecording system model 363.

During the data analysis phase, the HRV waveform is in the form of anR-R interval tachogram. The spectral analysis of this signal is obtainedfrom the successive discrete series of R-R duration values taken fromthe ECG signal sampled at 256 Hz and FFTed. All data from an in-the-labstudy is digitized by a Bio Pac 16 bit digitizer and software system.All post analysis, including FFTs, PSD and time domain measurements aredone with the DADiSP/32 digital signal processing software. All FFresponses from the Holter tape data which are artifact-free are used foranalysis.

For an in-lab study, HRV data is analyzed for 5 minutes before and for 5minutes during the practice of FF. The time domain traces are analyzedby obtaining the overall mean heart rate for both 5-minute periods andcalculating the standard deviation around that mean. FFTs of the timedomain data are analyzed by dividing the power spectra into threefrequency regions: VLF (0.01 to 0.05 Hz), LF (0.05 to 0.15 Hz) and HF(0.15 to 0.5 Hz). The integral of the total power in each of theseregions, the total power over all regions (VLF+LF+HF), the VLF/HF ratioand the LF/(VLF+HF) ratio are calculated for each individual in thebaseline and FF periods. The following criteria are used to classify thesubjects into two subgroups:

-   -   Entrainment mode, characterized by a very narrow band high        amplitude signal in the LF region of the HRV power spectrum,        with no other significant peaks in the VLF or HF region, and a        relatively harmonic signal (sine wave-like), in the time domain        trace of the HRV data; and    -   Internal coherence mode, characterized by an intentionally        produced very low amplitude signal across the entire HRV power        spectrum as compared to the baseline. The final discriminator of        this mode is the ECG amplitude spectrum, where the first seven        or so harmonics of the fundamental frequency are clearly        displayed, with very few intermediate frequencies having a        significant amplitude.

In general, the raw data baseline values to emotional expression valuesare analyzed for significance by using the Wilcoxon Signed Rank Test (T)utilizing the sum of the ranks for positive and negative differences foreach group. Wilcoxon p values were taken from the table of criticalvalues for the Wilcoxon Signed Rank Test (T). Typically, when a group isanalyzed as a whole there will be no change in heart rate or heart ratestandard deviation during the FF period. However, the power spectralanalysis usually shows a significant decrease in the VLF/HF ratio andsignificant increases in LF power (p<0.01), HF power (p<0.01) and in theLF/(VLF+HF) ratio (p<0.01), where p is probability.

A greatly simplified overview of some of the signals and functions ofthe human body are illustrated in FIG. 1. This figure is not intended tobe inclusive of all of the functions of the autonomic nervous system ofa human, but rather provides an exemplar of those signals and functionswhich are currently believed to be directly related to the operation ofthe heart. As illustrated in FIG. 1, the brainstem 5 receives variousinput signals, consisting of control and status information, fromthroughout the body. Thus, for example, the brainstem 5 receivesinformation relating to respiration, blood pressure, cardiac output,thermoregulation, and renin-angiotensin, as well as numerous othersystem inputs. Functioning as the control center of the central nervoussystem (CNS), the brainstem 5 continuously summarizes (Σ) all of thisafferent information and synthesizes appropriate outputs to the heart 7via either the sympathetic or parasympathetic subsystems.

Research has demonstrated that the output control signals of thesympathetic system, which is responsible for increased heart rate andblood pressure, such as in response to perceived danger, tend to berelatively low frequency (LF) rhythms. In contrast, the parasympatheticsystem, which operates to limit or suppress the effects of thesympathetic system, tend to be relatively high frequency (HF) signals.In general, the parasympathetic system tends to produce a quite, relaxedstate whereas the sympathetic a more active, excited state. For example,on inhalation, the parasympathetic system is inhibited and thesympathetic system is more active, resulting in an increase in heartrate. In contrast, on exhalation, the parasympathetic system is active,resulting in a stronger parasympathetic signal to the heart and heartrate is decreased.

The brainstem 5 also receives afferent information from the baroreceptornetwork, and other receptor neurons, located throughout the heart and inthe aortic arch of the heart 7, which are sensitive to stretch(pressure) and chemical changes within the heart 7. As the heart 7beats, and its walls swell, various baroreceptors are triggered,providing signals as a function of the heart beat, where increased heartrate is generally reflected by increased baroreceptor signals.

In response to the parasympathetic and sympathetic control signals fromthe brainstem 5, the heart rate 7 varies. The sinus node (SN) of theheart 7 is a group of cells which act as a natural pacemaker to initiatethe onset of the heart beat at a rate which is non-linearly related tothe relative strengths of these autonomic control signals. It has beendetermined that the heart beats with a certain variability, where thetime between beats is not constant but rather varies according to theshifting relative balance between the parasympathetic and sympatheticsignals. A typical heart rate variability (HRV) waveform, is illustratedin FIG. 1. Note that, as illustrated, the HRV is not constant butchanges with time, while still displaying a generally cyclical pattern.

FIG. 2 illustrates, by way of example, the transformation of an HRVwaveform, most conveniently measured in the time domain, into thefrequency domain. Such a transformation can be accomplished by standarddigital signal processing (DSP) methods, such as the well-known fastFourier transform (FFT). This results in a type of histogram thatmeasures the relative amplitudes for the different frequency components(rhythmic patterns) in the time domain waveform. Fast real-time rhythmsmap into peaks in the high frequency portion (right side) of thespectrum, whereas slow rhythms appear on the left, low frequency side.Any given peak may be due to a single rhythmic process or to a mixtureof rhythms with very similar frequencies. The latter will contribute toboth the height of a peak and increase its width. In the case of heartrate analysis, different frequencies (peaks) present in the powerspectrum are due to cyclic fluctuations in autonomic activity (i.e.,sympathetic and parasympathetic).

Once in the frequency domain, the power spectrum distribution (PSD) iscalculated using known DSP techniques, and plotted on the vertical axiswith frequency on the horizontal axis. In general, the power spectrum ofa waveform is a plot of the wave amplitude for each component squared,as a function of the frequency of that component. Such a plot revealsthe wave power, in units of energy per hertz, present in a smallfrequency range as a function of frequency, f. In the present example,the units of PSD are given as a power measurement, specifically squaredbeats-per-minute per second (BPM²/Hz, where Hertz (Hz) is frequency orcycles-per-second).

It is generally known that the mental and emotional state of a human hassignificant effects upon ANS activity, and, in particular, the balancebetween the parasympathetic and sympathetic subsystems. Such effects canbe clearly seen in the HRV waveforms. We have found that, in general,agitation or fear causes disorder, whereas emotions such as appreciationor love results in increased order. The latter state has been shown toencourage coupling between respiration and the HRV as well as otheroscillatory systems in the body. For purposes of the presentdescription, we shall refer to the state in which the HRV waveform andrespiratory waveform are operating at the same rate and near the 0.1 hzfrequency and appear as a sine wave as entrainment. As this mode ofheart function has been documented to correlate with increased balancebetween the sympathetic and parasympathetic branches of the nervoussystem it is also referred to as a state of “autonomic balance” (AB).The present invention is specifically intended to assist or facilitate auser thereof in achieving entrainment and AB at will. Once achieved,various well documented, beneficial physiological processes will beenhanced. Several embodiments of the present invention, discussed below,are specially designed to provide visual feedback to the user in amanner which tends to further strengthen and prolong the essentialcharacteristic of entrainment and AB.

Shown in FIG. 3A is the time domain HRV of a subject in variousemotional states; FIG. 3B shows the corresponding PSDs. A Baselinecondition is considered to be when the subject is in a normal, restingstate. A Disordered state is where the subject is feeling agitatedemotions such as anger or fear. Note the more irregular nature of thiswaveform, clearly showing the lower frequency components contributed bythe sympathetic system. In contrast, in an entrainment state, thewaveform is considerably more regular and orderly. Entrainment is acondition which we have shown can be attained by following a consciousplan or protocol for effecting a positive emotional state, such asappreciation or love.

As defined herein, these terms refer to the mental and emotional stateof the individual, and the graphs serve to illustrate theelectrophysiological characteristics of two, qualitatively distinct“heart function modes.” According to one analysis methodology, theEntrainment Mode is reached when frequency locking occurs between theHRV waveform and other biological oscillators such as respiration. Notethat other correlations may be made between the HRV waveform, as well asother parameters of the heart rate and its variability, and the generalstate of the subject, including other physiological systems. Thecorrespondence between HRV and the emotional and mental state of thesubject is provided herein as an exemplar, as there is a strong,documented relationship. However, alternate embodiments may correlateHRV waveforms with other functions and conditions, and are not limitedto those described herein as exemplars, but rather the analysis of theHRV waveform and the correlation with such conditions is achieved withthe present invention. Similarly, the correspondence to emotional andmental states is not limited to those illustrated in FIGS. 3A and 3B.

Shown in FIG. 4A are three simultaneously recorded body responses for anindividual taken before and after enacting the FF technique. The firstrecorded body response is HRV, displayed in beats per minute (BPM). Thesecond recorded body response is pulse transit time (PTT), which ismeasured in seconds. The third recorded body response is respiration,the amplitude of which is measured in millivolts (mV). As shown in FIG.4A, each of the recorded body responses undergo a dramatictransformation at approximately 300 seconds, the point at which theindividual performs the FF technique. At that time entrainment of theHRV, PTT and respiration waveforms is achieved. Such entrainment ischaracteristic of AB and increased physiological coherence.

Shown in FIG. 4B are the corresponding PSD for each of the recorded bodyresponses of FIG. 4A. Note, that the power spectra for each of therecorded body responses has a broad frequency range before performingFF. After performing FF, as illustrated in FIG. 4C, however, the powerspectra for each recorded body response has a much narrower frequencyrange, and in each case the maximum PSD is centered between a frequencyof approximately 0.1 Hz and 0.15 Hz. In addition, during entrainment,the maximum PSD for both HRV and PTT is much larger than that recordedbefore FF.

Shown in FIG. 5 is an entrainment apparatus 10 constructed in accordancewith one embodiment of the present invention. In this particularembodiment, entrainment apparatus 10 comprises a photo plethysmographicfinger sensor 12 and a computer system 14 having a monitor 15. Photoplethysmographic sensor 12 is electrically coupled to computer system 14via coupling cable 16.

During operation, an individual's finger 18 is placed in contact withthe plethysmographic sensor 12. In this particular embodiment, thesensor 12 includes a strap 20 which is placed over finger 18 to ensureproper contact between finger 18 and sensor 12. The photoplethysmographic sensor 12 detects the pulse wave produced by the heartbeat of the individual, by way of finger 18, and sends this informationto computer system 14. Computer system 14 collects and analyzes thisheart beat data, and determines the individual's level of entrainment. Arepresentation of the attained level of entrainment is displayed onmonitor 15.

Shown in FIG. 6 is a display output 22 produced by entrainment apparatus10 in accordance with one embodiment of the present invention. In thisparticular embodiment, the individual's heart rate, measured in beatsper minute (BPM), is graphically displayed for a selected time period.The individual's accumulated entrainment score for this same time periodis graphically displayed in reference to the calculated entrainmentzone. In addition, the individual's entrainment ratio and average heartrate are also graphically displayed for this same time period.

FIGS. 7A-7E illustrate a method of calculating an entrainment parameter(EP) according to the preferred embodiment of the present invention. Ingeneral, the method involves monitoring the beat-to-beat changes inheart rate, calculating the EP, and presenting a representation of thecategorization of the calculated EP. The method begins at start block30. The process is initialized at step 32, where HRV data is obtainedand processed in preparation for the next step. At step 34 anentrainment parameter (EP) and score are calculated. The entrainmentparameter is determined by the power distribution of the HRV processeddata, and the score is a historical indication of the EP. The EP andscore are then presented at step 36, which may involve providing thisinformation to a display terminal. The process continues to decisiondiamond 38, to determine if the process is to terminate or end. If theprocess is to end, processing continues to step 40 where the process isterminated. If the process is not to end, process flow returns to block34.

The process is further detailed in FIG. 7B, where the heart beat ismonitored at step 42. This may involve using electrical sensingapparatus, such as an electrocardiograph (ECG), light sensing apparatus,such as the photo plethysmographic sensor 12, or any other apparatus ormeans whereby each heart beat can be ascertained substantially in realtime. For example, at regular time intervals, say 100 times per second,the output of sensor 12 is sampled and digitized using a conventionalanalog-to-digital (A/D) converter (not shown). At step 44, the rawsamples are stored. This raw data is basically a record of each heartbeat and the relative time of its occurrence. The stored raw data can bethought of as comprising inter-beat-interval (IBI) information, fromwhich the time interval between beats can be determined. It is the IBIvariation which is generally referred to as “heart rate variability” orsimply HRV.

Note that in monitoring the heart beat, artifacts, such as noise and/ormisreads, may have a tendency to disturb the process. An optional stepis provided at block 46 where the artifacts and other artificiallyintroduced noise are rejected. This may be done using a conventional DSPartifact rejection technique. Block 46 is further detailed in FIG. 7E,startingRavg_(i−1)(1−P min)at decision diamond 94. Here the current IBI, referred to as IBI_(i) iscompared to an absolute minimum interval between beats (Amin) and to anabsolute maximum interval between beats (Amax). Amin and Amax arereflect the actual range within which the human heart beat falls. Forexample, Amax and Amin indicate that IBI is either too long and tooshort respectively, and IBI does not normally occur at that value; thusthese conditions are used to detect artifacts which are not accuratedata. If IBI_(i) falls between these two extremes processing continuesto step 96. If IBI_(i) does not fall within this range, no further checkis made and processing jumps to step 98 for elimination of bad IBI_(i)data. Note that a running average (Ravg) is calculated for IBI values. Arange of Ravg values is determined for each IBI_(i) and is then used toverify then next value, IBI_(i+1). The range of Ravg values isdetermined as a percentage of the IBI value. For evaluation of IBI_(i)the range of Ravg values for IBI_(i−1), is used. In one embodiment, therange is defined between Rmin_(i−1) and Rmax_(i−1), where Rmin_(i−1) isRavg_(i−1)−30% and Rmax_(i−1) is Ravg_(i−1)+30%. IBI_(i) falls withinthis range if it satisfies the following relationship:IBI _(i)ε[Ravg_(i−1)(1−Pmin),Ravg_(i−1)(1+Pmax)]

Continuing at step 96, if IBI_(i) is within this range, processing jumpsto step 100. If IBI_(i) is not within this range, processing continuesto step 98 where IBI_(i) is eliminated as bad data. In a preferredembodiment, if too many errors are encountered, calculation is frozenuntil sufficient good data is received to warrant continuing. Sufficientgood data is indicated by the following relationship:Amin<∀ε[IBI _(j) , IBI _(k) ]<Amaxwherein IBI includes values IBI_(j), . . . IBI_(k). At step 100 therunning average of IBI_(i) is calculated as Ravg_(i). At step 102 theminimum range of Ravg for IBI_(i) is calculated as Rmin_(i). At step 104the maximum range of Ravg for IBI_(i) is calculated as Rmax_(i). Thesevalues will be used to verify the next IBI value, IBI_(i+1). Processingthen continues to decision diamond 106 to determine if further IBIprocessing is to be done, and if so processing returns to decisiondiamond 94. If not, processing continues to step 48.

At step 48, a conveniently sized segment of the raw data samples, say 64seconds, is selected, and then linearly interpolated using standard DSPtechniques, at step 50. To facilitate discrimination, the raw IBI datapoints have been scaled by 1000, i.e., converted to milliseconds. TheHRV graph shown in FIG. 8A illustrates a representative set of scaledIBI data and the linearly interpolated data points, where the IBI datapoints are indicated by a black dot and the interpolated data points areindicated by “x.”

At step 52, the selected segment of HRV data is demeaned and detrendedby subtracting a linear regression least squared fit line (a common DSPtechnique) to center the waveform with respect to the vertical axis, andto remove any tendency of the waveform to slowly decrease or increase.As illustrated in FIG. 8B, the HRV segment exhibits a decreasing trendover time, as can be seen from the superimposed linear regression line.

As will be clear to those skilled in this art, the segmentation processperformed in step 48 has the undesirable side effect of convolving theHRV data with a square wave, and thus tends to introduce noise at theboundaries between each segment. For example, where the number of datapoints in each segment is 128, there will be significant noiseintroduced between sample 128 and 129. A well known DSP technique,called Hanning windowing, effectively weights the center data points ofthe segment more heavily than those at the edges to reduce the effectsof this noise. As used in the present embodiment, the Hanning windowequation uses a cosine taper as follows:W(n)=0.5−0.5 cos(2π/N*n)where N is the total number of data points in the segment, and n=[1,N−1]. At step 54, such a Hanning window is applied to the detrended datato eliminate the segmentation noise. As illustrated in FIG. 8C, theresultant HRV waveform is zero-referenced and exhibits no trend. Itshould be recognized that various other alternate methods or techniquescan be employed to remove such noise as may have been introduced asartifacts of the recording, interpolating or segmentation processes.

At step 56, a user-established system control variable is examined todetermine what type of spectrum analysis needs to be performed. If amagnitude spectrum is selected, an FFT is performed at step 58 togenerate a magnitude spectrum. On the other hand, if a power spectrum isselected, the PSD of the detrended data is calculated, in step 60, usinga standard FFT. This PSD is then normalized, at step 62, by dividing bythe length of the segment in seconds (see, step 33). For example, if thenumber of data points was selected to be 128 points, the PSD is dividedby 64, the duration of the segment, i.e., 64 seconds. This makes theunits of power ms²/Hz. Note that such a normalization process is notnecessary if the magnitude spectrum is used.

The result after step 58 or 62 is illustrated in FIG. 8D, where thehorizontal axis represents frequency (Hz) and the vertical axisrepresents power (ms²/Hz). Note that HRV is portrayed in the form of abar chart, wherein each bar represents the power contained in the HRVsignal within a respective, narrow band of frequencies comprising a“bin,” as illustrated in FIG. 8D. For convenience of reference, the binsare logically numbered sequentially, starting with bin 1 on the farleft, and continuing to bin 64 on the far right, where each bincorresponds to a frequency. At step 64, a pair of user-selected systemcontrol variables is examined to select the range of bins from which thehighest local peak will be selected. As it can be anticipated that thedesired peak will be within a certain frequency range, it is neithernecessary nor reasonable to consider the entire PSD. According to oneembodiment, the starting search bin is selected by a variable “searchbin start” (SBS), while the ending search bin is selected by a variable“search bin end” (SBE). For the example illustrated in FIG. 8D, the SBSis equal to 3 and the SBE is equal to 18, comprising the search range ofbins 3, 4, 5, . . . , 18.

At step 66 (FIG. 7C), a search is made, within the bin range selected instep 64, for all local peaks in the HRV spectrum, each being representedby the single bin having the highest power level, i.e., the binunderneath the respective peak. Next, the bin representing the highestpeak within the bin range is selected. In the example shown in FIG. 8D,there are three peaks within the bin range of bin 3 to bin 18. Thehighest peak is located at bin 5. Note that the first, and absolutelargest, peak is represented by bin 2, so bin 3 is not considered torepresent a peak.

Once the highest peak within the selected bin range has been determined,an entrainment parameter (EP) is calculated to indicate the energy ofthe wave in the entrainment area in relation to the total energy in thePSD. To calculate the EP, at step 66, the “width” of the peak isdetermined from a pair of user-selected variables: P1, which defines thenumber of bins to the left of the peak bin, and P2, which defines thenumber of bins to the right of the peak bin. Note that P1 and P2 may bedifferent if an asymmetric distribution is desired. The total energy ofthe peak, Psum, is then calculated as the sum of the power values of allbins in the range [(Peak−P1), (Peak+P2)] at step 68.

Next, at step 70, the total power below the peak pulse (Pbelow) iscalculated. The relevant range is determined by a pair of user-selectedvariables: B1 and B2. The value of Pbelow is a summation of the powervalues of all bins in the range [B1, B2]. Similarly, at step 72, thetotal power above the peak (Pabove) is calculated, within a relevantrange determined by a pair of user-selected variables: A1 and A2. Thevalue of Pabove is a summation of the power values of all bins in therange [A1, A2]. This is clearly illustrated in FIG. 8E. Finally, at step74, EP is calculated according to the following equation:EP=(Psum/Pbelow)*(Psum/Pabove).

At step 76, the EP value is then “scored” according to a plurality ofuser-selected entrainment level thresholds. For example, three stages ofentrainment can be conveniently defined using only two variables, NLT1and NLT2, each of which represents a respective value of EP. In such anembodiment, for EP below NLT1, the subject may be considered as nothaving achieved significant entrainment, and is given a score of “0”.For EP above NLT1 and below NLT2, the subject is considered to haveachieved mild entrainment, and is given a score of “1”. For EP aboveNLT2, the subject is considered to have achieved full entrainment, andis given a score of “2”. Of course, other criteria may be used todetermine achieved entrainment level.

In general, maximum entrainment is reached when the peak pulse containsa very large portion of the total power. A particularly high EP isillustrated in FIG. 8F, where Psum is great compared to both Pbelow andPabove. This indicates that most of the power is concentrated at thissmall group of frequencies. Thus, EP tends to emphasize the conditionwherein the majority of the power is concentrated within a selected,relatively narrow range of frequency bins. On the other hand, it iscertainly possible to devise alternate calculations which will reflectconcentration of significant levels of power distributed over a broaderrange of frequency bins.

At step 78, the most recently calculated score is recorded and anaccumulated score is calculated based on prior, historical scores,referred to as accumulated scores. At step 36, the actual EP result andaccumulated scores are prepared for presentation to the user as a systemoutput. This preparation involves steps such as 76 and 78.

At decision step 80, it is determined if the user desires thisinformation to be simply output on a status screen of the computer, in apresentation format such as that shown by way of example in FIG. 6. Inthe preferred embodiment of the present invention, the user can elect tohave this information control a game, such as the balloon game shown inFIG. 10. If the user so selects, at decision step 80, EP is compared toa various threshold levels and assigned an EP score accordingly.

According to one embodiment, EP is assigned a score selected from theset of {0, 1, 2}. The score values have the following significance: EPScore EP value Entrainment 0 EP < level1 Low 1 level1 < EP ≦ level2Medium 2 level2 < EP HighAccording to one embodiment, level1 is set to 0.9, and level2 is set to7.0, to provide a convenient distribution. In a computer programimplementing this embodiment, these levels are provided as floatingpoint values. Alternate embodiments may use additional levels, or mayuse two levels.

If the user selects a nonstatic format, processing continues to step 84of FIG. 7D, where the accumulated score, “Ascore,” is calculated basedon the historical information of the EP and EP score values. Ascore isthen calculated based on the score value, and the previous score value(prescore). This calculation is performed according to the followingscheme: EP Score EP Prescore Ascore(i) 2 0 Ascore(i − 1) + 1 1 0Ascore(i − 1) + 1 0 0 Ascore(i − 1) − 2 2 1 Ascore(i − 1) + 1 1 1Ascore(i − 1) + 1 0 1 Ascore(i − 1) − 1 2 2 Ascore(i − 1) + 2 1 2Ascore(i − 1) + 1 0 2 Ascore(i − 1) − 2According to one embodiment, Ascore has values in the range of {0, 1, 2,. . . 100}, however alternate embodiments may use an alternate range ofvalues. The above scheme provides scaled response to the EP, whereAscore slowly increases while remaining in medium entrainment, butquickly increases while remaining in high entrainment. Similarly, thisscheme provides a quick decrease while remaining in the low entrainment.

Ascore information may be then be used to provide a graphical display.One embodiment, illustrated in FIG. 7D begins at decision diamond 84 todetermine the value of Ascore_(i) with respect to Ascore Ascore_(i) isthe current calculated value of Ascore, and Ascore_(i−1) is the previouscalculated value of Ascore.

If Ascore_(i) is equal to Ascore_(i−1), processing returns to step 38without effecting any change in the graphical display. Note thatalternate embodiments may include additional steps which provide thisinformation to the display. If Ascore_(i) is greater than Ascore_(i-1),processing continues to decision diamond 86 to determine if Ascore_(i)has reached an Ascore_(max) value. According to one embodiment,Ascore_(max) is equal to 100. If Ascore_(i) is not greater thanAscore_(max) processing continues to step 88. At step 88 a graphicalelement transitions toward a goal. In one embodiment, the graphicalelement is a balloon, and the transition is to rise vertically into theair. In an alternate embodiment, the graphical element is a rainbow, andthe rainbow begins to fill in colors to reach a pot of gold. Once therainbow reaches the pot of gold, the pot begins to fill with coins andmay overspill. In still another embodiment, a peaceful scene is slowlyfilled in with color and detail. Alternate embodiments may include otherscenes, icons, or images, and may include obstacles to be overcome orvarious stages to be reached. Processing then returns to step 38.

Continuing with FIG. 7D, If Ascore_(i) is greater than Ascore_(max),processing returns to step 38 without effecting any change in thegraphical display. Note that alternate embodiments may includeadditional steps which provide this information to the display.

Returning to step 84 of FIG. 7D, if Ascore_(i) is less thanAscore_(i−1), processing continues to decision diamond 90 to determineif Ascore_(i) has reached an Ascore_(min) value. According to oneembodiment, Ascore_(min) is equal to 0. If Ascore_(i) is not less thanAscore_(min), processing continues to step 92. At step 92 a graphicalelement transitions away from a goal. In one embodiment where thegraphical element is a balloon, the transition is to lower verticallytoward the ground. In an alternate embodiment where the graphicalelement is a rainbow, the rainbow begins to lose colors and separatefrom a pot of gold. If the pot of gold includes gold coins, these coinsare removed. In still another embodiment where a peaceful scene isdisplayed, color and detail are slowly removed from the display.Alternate embodiments may include other scenes, icons, or images, andmay include obstacles to be overcome or various stages to be reached.Processing then returns to step 38.

At decision diamond 90, if Ascore_(i) is less than Ascore_(min),processing continues to step 38 without effecting any change in thegraphical display. Note that alternate embodiments may includeadditional steps which provide this information to the display.

Note that in an alternate embodiment, a graphical element, such as aballoon figure, may be manipulated in an appropriate way, such as risingbased directly on the EP score. As illustrated in FIG. 10, a hot airballoon is illustrated rising in the sky indicating a state ofentrainment. As discussed hereinbelow, the background of the sceneincludes a grassy field with various obstacles positioned horizontallyacross the screen. The balloon must rise above various heights to avoideach obstacle. This display provides a visual indication of the state ofentrainment and provide a visual reward for achieving entrainment.Control of the balloon illustrates the individual's control of theemotional and/or mental state. In alternate embodiment, other graphicscenarios may be used, which accomplish a particular goal as the EPscore value reflects entrainment.

In accordance with the present invention, the method is recursive,performing the various steps described above periodically, say every 5seconds or so. According to one embodiment, the method is implemented inthe form of a software program which can be stored and distributed in acomputer readable medium. The software is then operated on a personalcomputer, or a hand held computing device, or any other medium capableof operating a software program and providing a user informationdisplay.

INDUSTRIAL APPLICABILITY

Shown in FIG. 9, is an entrainment apparatus 100 in accordance with analternative embodiment of the present invention. In this particularembodiment, entrainment apparatus 100 is hand held unit which allows anindividual to determine his or her level of entrainment. In oneembodiment, entrainment apparatus 100 comprises a photo plethysmographicsensor 102, a data processing system 104, and a display 106.

In one embodiment, an individual places a finger within a receptaclelocated on the back of entrainment apparatus 29 which contains photoplethysmographic sensor 102. Photo plethysmographic sensor 102 sensesthe heart beat of the individual, by way of the finger, and sends thisheart beat information to data processing system 104. Data processingsystem 104 collects and analyzes this heart beat data, and determinesthe individuals level of entrainment. A display output containinginformation relating to the individuals entrainment level is thengenerated by data processing system 104 and displayed on display 106. Inone form, information relating to the individuals entrainment ratio isdisplayed on display 106, and a mode allows the users to review his orher low entrainment ratio, medium entrainment ratio or high entrainmentratio.

In an alternative embodiment, the sensor 102 comprises a vest or strapcontaining ECG electrodes. The individual places the vest on and thenelectrically couples it to the hand held portion of entrainmentapparatus 100. The vest or strap is then used to sense the individualsheart beat and send heart beat information to data processing system104.

Shown in FIG. 10 is a presentation format 24 produced by entrainmentapparatus 10 in accordance with an alternative embodiment of the presentinvention. In this particular embodiment, a hot air balloon floatsacross a country landscape and the background scenery scrolls slowly byas the balloon floats into the sky based on the individual's entrainmentlevel. If the individual does not maintain entrainment, the balloonsinks to the ground. Obstacles like a brick wall or a tree, as shown inFIG. 10, are presented during the course of the flight. If theindividual's entrainment level is not high enough to clear one of theseobstacles, the balloon's flight is impeded until an entrainment levelhigh enough to raise the balloon above the obstacle is achieved. Thecalculated entrainment zone defines the balloon's climbing slope forhigh entrainment and for low entrainment.

Shown in FIG. 11 is an alternative presentation format 26 produced byentrainment apparatus 10 in accordance with an alternative embodiment ofthe present invention. In this particular embodiment, a rainbow growstoward a pot when an individual is in a state of entrainment. Growth ofthe rainbow toward the pot is smooth and steady while the individualmaintains entrainment, but the rainbow recedes if the individual doesnot maintain entrainment. Once the rainbow reaches the pot, gold coinsaccumulate and fill the pot if the individual continues to maintainentrainment. For example, one coin is added to the pot for each fivesecond time period of medium entrainment and two coins are added to thepot for each five second time period of high entrainment. A total scoreis then presented at the end of a selected time period.

Shown in FIG. 12 is yet another possible presentation format 28 producedby entrainment apparatus 10 in accordance with an alternative embodimentof the present invention. In this particular embodiment, a nature scenechanges with time as the individual maintains entrainment. For example,the scene changes for every 10 seconds that entrainment is held. Ifentrainment is low or not maintained the scene does not change.

Alternate embodiments may employ a variety of display formats includingdetailed information, graphical information, graphic images, videoimages, and audio images. According to one embodiment, the level ofentrainment controls the volume on a music delivery system. This may beimplemented based on the EP value, where the volume increases withincreasing EP and decreases with decreasing EP. The system may beoptimized by using music especially designed to enhance the entrainmentprocess. Further, in one embodiment, the music changes style withentrainment level. Additionally audio controllers may provide verbalmessages.

It is possible to combine the game functionality with a hand-held devicein the form of a toy. In one embodiment, a crystal ball lights up andglows brighter as entrainment is maintained. The light may change coloras entrainment levels are reached. Again, the color of the light isdesigned to optimize the entrainment method. The crystal ball may be ahand-held, or other convenient device, and may be battery-operatedand/or portable to allow enhanced life performance. Alternateembodiments use toy designs and methods, such as radio-controlled toys,such as cars, trucks, and animals. The toy operation is based on thelevel of entrainment. In still other embodiments, stuffed animals ortoys emit harmonizing sounds and music based on the level ofentrainment.

For visual display embodiments, one embodiment begins with a solidbackground of dots, which dissolve as higher levels of entrainment arereached to reveal a graphic image, such as a 3-dimensional image. Asentrainment reduces to a lower level, the dots fill the screen again.

Additionally, various computer games may use entrainment levels and/orthe EP value and/or the accumulated scores as triggers to produce variedresults. For example, in action games entrainment triggers access to newadventures as the game unfolds. The adventure plays out differentlydepending on the pattern of entrainment, i.e whether entrainment ismaintained at one level, or oscillates between levels, or increases, orincreases. It is possible to combine keyboard strokes and mouse and/orjoystick movements to facilitate the game. In one embodiment, a lockeddoor is only unlocked when entrainment reaches a certain level. It maybe necessary to maintain entrainment at that level for a predeterminedamount of time. The objects of such games may include spacecraft movingthrough space, animals in a jungle, race cars on a track, or any otherimagery applicable to a game.

Various images are more helpful in achieving entrainment for anindividual than other images. Those images are selected based onpredetermined visual and auditory rhythm, and may be specific to theindividual and may change from day to day. In one embodiment, a screensaver provides a visual image having a predetermined visual and auditoryrhythm, and includes options for the individual to select based onpersonal preferences. Where feedback is provided to the screensaverprogram, the screen saver program may perform adjustments to optimizethe effects for the individual. Our research suggests several criteriathat tend to enhance entrainment. For example, circles, and shapes withrounded edges or curved lines tend to enhance entrainment better thansquares, having angular, jagged, or sharp lines. Additionally, movementof the images should be slow, coherent and rhythmic, and transitions aresmooth, slow and flowing. Colors and rhythms should oscillate, where theillusion is of inward and outward movement simultaneously. Movementsshould transition smoothly, without jarring or erratic motion.

The present invention is also applicable to sports endeavors andathletes, particularly those performing in high stress situations, suchas a critical hole in golf. The games, devices, and techniques allow theathlete to practicing attaining entrainment and thus gain familiaritywith this feeling state which can then be more easily accessed duringactual games for improved performance. Various game embodiments may bedesigned for the sports enthusiast. For example, a beautiful golf coursecomes into view as entrainment is reached. Other games could include agolfer swinging a club or hitting a ball, where the path of flight anddistance are determined by the degree of entrainment prior to the shot.In one embodiment, the game keeps score, and if not entrained, the ballgoes into a sandtrap or lands in the rough or water or other hazard.Prolonged states of entrainment produces a hole in one, or other reward.Alternate embodiments may employ a similar strategy for other sports,such as baseball, basketball, football, and other popular sports.

In one embodiment, a vehicle is stuck in a traffic jam in Silicon Valleyand moves proportionally to entrainment. As the car moves faster itheads for a scenic place. Note that these games may be operated on apersonal computer, or other display device, or may be operated on aportable device. The portable device is highly desirable, as the valueof entrainment on reducing stress and increasing the quality of life ismost necessary during everyday life events. For example, a businessdevice may combine a calculator or personal planner with the presentinvention, to allow a business person to utilize the device at abusiness meeting or negotiations without the knowledge of those around.In one embodiment, a touchpad used for manipulating a pointer on adisplay screen is also used to monitor heart beat data. It is alsopossible to have a device which is accessed by multiple persons. Hereprior to beginning an activity, such as a business meeting or a sportsevent, each member must reach a predetermined level of entrainment for apredetermined period of time. Satisfaction of which may be indicated bya particular color light or a specified sound.

A hand-held device is applicable to education, where it effectivelyprograms the neural network of the brain of the student allowingfamiliarity with the feeling of coherent and entrained states. Oncedeveloped, these states will carry over throughout adult life toinfluence attainment and maintenance of emotional balance andphysiological coherence. By providing an easy to use format, geared toyounger users, the present invention encourages them to learn how tocreate coherent and entrained heart rhythms. Cartoon characters, animalsand popular images may be animated and provide instructions for reachingentrainment and rewards for success.

The present invention is also applicable to the medical community andmedical applications. As the entrained state provides an efficientphysiological state, by putting less wear and tear on the glands andorgans, the present method of reaching and monitoring the entrainmentstate is a nonintrusive preventive medical technique. Our researchsuggests that by teaching individuals with certain pathologies toself-generate health, high performance heart rhythms that the bodies ownregenerative systems seem to be activated and healing is facilitated.Applications of the present invention for such use include pain control,blood pressure control, arrythmia stabilization, and diabeticmanagement.

Research suggests that afferent input from the heart at the brain stemlevel modulates the ability of pain signals to transmit from the nervoussystem to the brain. The level of entrainment is proportional toafferent input, thereby affecting the inhibition of pain signals fromthe heart to the brain. A subject experiencing pain may use the presentinvention to reach a state of entrainment, where the pain is lessened.Further, an entrained state leads to more efficient blood flowthroughout the organism and may reduce the deleterious effects of highblood pressure. In one embodiment, a game includes a visual image of thehuman body including arteries and major blood vessels. The level ofentrainment controls the images of blood flow through the body. Thedisplay illustrates the functioning of the body internally, andindicates the specific differences in heart function during stress andhigh emotions, as compared to entrainment and coherence. As the rhythmsof the heart become entrained, the blood flow images change toillustrate the efficient use of energy.

Still additional benefits of reaching and maintaining a state ofentrainment include the efficient functioning of the autonomic nervoussystems. In one embodiment, a game is used which provides visual imagesof the electrical signals of the nervous systems. Pulsating signals aredisplayed throughout the human system and are transmitted according tosensor detection from the subject. The goal of this game is to changethe image such that the systems function efficiently, and to reduce oreliminate the frayed or frazzled images.

Our research has further shown that emotional self-management andphysiological coherence are effective in reducing depression, anxiety,and other emotional stress, and also in improving glycemic control indiabetic populations. Additionally, maintaining an entrainment state isgenerally beneficial in treating anxiety, general depression, and otheremotional disorders. For example, one embodiment provides a device formonitoring the autonomic balance according to the present inventionprior to retiring for rest. This is particularly beneficial in thetreatment of sleep disorders, and allows the subject to shift heartrhythms which tends to enhance sleep.

Additionally, the present invention is applicable to impulse control,providing training to help overcome eating disorders, anger, and/oraddiction. Our research suggests that the present invention isbeneficial in learning stress management, and emotional self-management.In one embodiment, a visual display is provided to illustrate othersystems within the body, such as neural and hormonal systems, wheresignals are displayed moving from the heart to the brain. Here theeffects of these signals are clearly seen, and may be controlled byattaining a state of entrainment.

Although various preferred embodiments of the present invention havebeen disclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and/or substitutionsare possible without departing from the scope and spirit of the presentinvention as disclosed in the claims.

1. A method, characterized by: sampling a heart beat of a subject;determining a heart rate variability (HRV) of the heart rate as afunction of time (HRV(t)); expressing HRV(t) as a function of frequency(HRV(f)); determining a distribution of frequencies in HRV(f); selectinga peak frequency of HRV(f); determining the energy in said peakfrequency (E_(peak)); determining the energy in frequencies below saidpeak frequency (E_(below)) and above said peak frequency (E_(above));determining a ratio of E_(peak) to E_(below) and E_(above); andproviding to the subject, in a first presentation format, arepresentation of a first parameter related to said ratio.
 2. The methodas in claim 1, wherein the ratio is characterized as:$\frac{E_{peak}}{\left( {E_{below}*E_{above}} \right)}$
 3. The method asin claim 2, wherein the first parameter is characterized by anentrainment parameter (EP).
 4. The method as in claim 3, furthercharacterized by the step of: demeaning and detrending the HRV(t). 5.The method as in claim 2, wherein the frequency distribution determiningstep is further characterized as: determining a power spectrumdistribution (PSD) of frequencies in HRV(f);
 6. The method as in claim1, wherein the method is practiced in a data processing system includinga display, wherein the method is further characterized by the steps of:determining an entrainment parameter (EP), related to the ratio; inresponse to a first EP value, providing a first image on the display;and in response to a second EP value, different from the first EP value,altering the first image on the display.
 7. The method as in claim 6,further characterized as: wherein the first image includes a graphicelement in a first position; wherein if the second EP value is greaterthan the first EP value, the graphic element transitions toward a goal;and wherein if the second EP value is less than the first EP value, thegraphic element transitions away from the goal.
 8. A software programperforming the method of claim
 1. 9. The method as in claim 1, furthercharacterized by the steps of: digital signal processing the HRV toprovide a plurality of bins corresponding to frequencies; selecting thepeak within a first predetermined range of the frequencies; calculatingthe power in the bins corresponding to the peak; calculating the powerin the bins below those corresponding to the peak; and calculating thepower in the bins above those corresponding to the peak.
 10. Anapparatus, characterized by: sampling means adapted to sample a heartbeat of a subject for a first predetermined time period; a display unit;a processing unit coupled to the sampling means and the display unit,wherein the processing unit is adapted to: determine a heart ratevariability (HRV) of the heart beat as a function of time by measuringthe interval between each beat during the first predetermined timeperiod; determine a frequency distribution of the HRV, the frequencydistribution having at least one peak including a first number offrequencies; calculate a first parameter of the frequency distributionof the HRV, wherein the first parameter is a ratio of the area under theat least one peak to the area under the rest of the frequencydistribution; and output the first parameter to the display unit forpresentation to the subject.
 11. A method, comprising the steps of:receiving heart rate variability (HRV) information, the HRV informationcomprising the time intervals between each heart beat of a subjectduring a first predetermined time period; expressing the HRV as afunction of frequency; determining the power in said HRV over a firstrange of frequencies; selecting a power peak in said first range offrequencies; calculating a first parameter relating the power in saidselected power peak to the power in said HRV over a second range offrequencies; presenting the first parameter to the subject.